Version 5 Introduces Breaking Change Preventing Calling load twice

[robert-nash]

https://github.com/JiriHoffmann/react-native-clusterer/blame/9025cbb14306574a9d87be790014d699dfb25832/src/Supercluster.ts#L47

I was previously calling .load on an instance of Supercluster repeatedly in response to changes to the underlying data. This now raises the error "The .load() method can only be called once."

I'm not sure if the way I was doing it before was wrong (although it seemed to work) but I think this could potentially be mentioned in the changelog.

I also wonder if the fact that .load should not be called multiple times should be clearer? I can see that the documentation for the load method says "Once loaded, index is immutable." however I feel this is slightly ambiguous.

Thanks for your work!